FIG. 1 is a diagram depicting a typical prior art telecommunications network, in which three site locations have a need for telecommunications therebetween. In the prior art, dedicated lines, such as single user phone lines, are leased and connected between each of the three sites. For greater bandwidth, these interconnecting leased lines may be T1 lines, which are equivalent to 24 single voice channels, or a data rate of 1.544 megabits/second, or T3 lines, having a bandwidth equivalent to a plurality of T1 lines, having a bandwidth of 44.736 megabits/second. Such lines are expensive to lease, and are somewhat clumsy when a user's needs vary or are significantly less than the full bandwidth provided by a T1 or T3 leased line, since the user must lease and pay for unneeded capacity. While reference is made in this application to T1 and T3 lines and capacities, it is understood that in other parts of the world E1 and E3 lines are the standards, with an E1 line having a capacity of 32 voice channels as compared with the 24 voice channels of the T1 standard.
While there exists prior art switches which allow the multiplexing of a plurality of fractional T1 bandwidth lines into a single T1 signal, a more modern approach is the use of an asynchronous transfer mode (ATM) network, as depicted in FIG. 2. FIG. 2 depicts a system including an ATM network 201 which includes a plurality of high bandwidth data switches 202-1 through 202-N, and appropriate high speed links therebetween. Such links are typically T3 links at the present time. ATM network 201 is maintained by a long distance carrier company, such as AT&T or MCI, the local phone company, an international carrier, or private network. Individual users located at sites 205-1 through 205-N connect into ATM network 201 at their local ATM network access points and share resources of the ATM network in order to communicate with a distant site. This sharing of ATM network resources provides for more economical telecommunications in that ATM network facilities are shared among a number of users in a time varying fashion to account for variation in individual site needs over time. The use of the ATM network also reduces the number of telecommunication lines, since a complete permutation of telecommunication lines between sites which must communicate with each other is no longer needed.
However, there remains a difficulty in the implementation of the ATM network in that there is a mismatch between the T3 minimum bandwidth access to switches 202-1 through 202-N of ATM network 201, and the T1 or fractional T1 bandwidth of a number of users seeking access to ATM network 201. This difficulty is exacerbated by the fact that there exists a number of data communication standards which are commonly used and which are not compatible with a single T3 signal. Such existing widely used standards include the previously mentioned 24 voice channels multiplexed on a T1 carrier, frame relay protocol, switched multi-megabit data service (SMDS) interface protocol (SIP) relay formed from a plurality of 56k bit per second data channels, video signals (for example, MPEG standard), and the ATM protocol itself.